1. Field of the Invention
This invention relates generally to an automatic centering method for a video camera having a plurality of pick-up tubes and, in particular, is directed to an automatic centering method suitable for use with a three pick-up tube type video camera by which the centers of picture screens of three pick-up tubes can automatically be made coincident with one another.
2. Description of the Prior Art
In the prior art, when the centering of a video camera of, for example, the three pick-up type is carried out, a predetermined test chart such as a stripe pattern and so on is picked up by the pick-up tubes and while the pictures shot by the pick-up tubes are checked by a television monitor and so on, the deflection systems and the like of the respective pick-up tubes are adjusted.
Such a prior art centering method, however, always requires the test chart and, the deflection system and so on must be adjusted very skillfully.
On the other hand, as is disclosed in a Japanese patent application No. 175427/1983 previously proposed by the present applicant, it was considered that an arbitrary object be shot by a pick-up tube and the centering thereof be carried out automatically by using a microcomputer.
In this case, however, it became clear that depending on the content of the object, the centering was not carried out correctly but the displacement among the centerings was increased.
That is, as shown in FIGS. 2A and 2B, when objects which are the same in displacement amount (shown by an arrow) but different ones are shot or picked up, in the case of FIG. 2A, the objects are converged to the nearby pattern (shown by a double arrow) to thereby establish the correct centering, while the case of FIG. 2B, when the objects are converged to the nearby pattern (shown by the double arrow), the displacement amount of the centerings is increased, on the contrary.
Accordingly, if a picture is taken by the video camera with the displaced centering, it becomes impossible to reproduce the picture correctly. As a result, the pictures taken by the video camera become useless.